Hydrospring shock absorber



May 611952 l. P. GAY 2,595,239

HYDROSPRING sHocx ABSORBER Filed June 50, 1948 wwzhfegg Patented May 6,1952 UNITED STATES ATSENT OFFICE (Qranted under the act f.` Mar-.ch 3,1883-, amended April, so, 1928.;v 3.70. Q- G. 7.5.7)A

The invention described herein maybe manufactured and ued by or for theGovernment forgovernmental purposes without the payment or' any4 royaltythereon.

invention relates to shock absorbers for yieldingly connecting twopartsof a mechanism subjected to. large-amplitude shocks, and is suitable foruse with recoil mechanism for guns, shock absorbers for airplane landinggear, etc.

The primary object ofthe invention is the provision Qf a shock absorberusing a spring as an energy-.storing device, together with hydraulicmeansfor reducing the dynamic stress on the spring when the initialshock is of very high velocity, as occurs, for example in a gun recoilmechanism. Other objects are to reduce the weight and size of4 theabsorber for a given ca. pacity, compared to former designs; to enablethe. use ofi a friction ring spring of short stroke to absorb. shocks oflarge amplitude, and to provide-a shock or recoil-absorbing actionsimilar to that heretofore obtained only with hydro-pneumaticsystems,but with a much simpler and less complicated construction.

Furtherobjects and advantages of my invention will now` fully appear inthe following de-V scription off-the preferred embodiments of myinvention, inv which:

s Figure 1 is a longitudinal cross-sectional schematic view of'a shockabsorber showing the princi-ples of my invention,

Figure 2 is a longitudinal cross-sectional schematic View. showing theVshock absorber of my invention applied to a gun as a recoil mechanism,`the gun being in the battery position,

Figure 3 shows the device of Figure 2 but with the- -gun in the`maxim.umY recoil position,

rieures 4 and A5,. are. Schematic views 0f the asymmetrical"floatnaerlflcerart of my device,

sbewifng the dineren operation in different die' resuena.

Figli-.reo is `a `sectional-view of a counterrecoil helling means. whichmay Optcnallv be incorporatedinto.-

invention.

Referring to Figure 1 the cylinder I is fastened in. any. convenientmanner to one of the relatlvelymovable member Whose relative motion`iste be cushioned, and the plunger 2 is fastened verlegt manner. tethe. ether of Seid @mbersasbv tbreadedrod i Pluneer 2 cornnrises twocoaxial cylinders 5 and 4, of diierent diameters as shown, each slidablein an opposite, end wall E Vand 'I of cylinder I, through asuitableduid-tight packing schematically in- `dicatedat 6"- and 'Il'. A floatingpiston il Slidably 2 engages the inner wall of cylinder I. and the outerWall of cylinder 4 in fluid-tight fashion, schematically represented bypacking rines 9er-1d I I. Floating piston 8 bears against the/free endof spring. I2, the other end-of which tears against the end wall 6 ofcylinder- I. All of the remaining space in the cylinder I on the otherside, of floating piston 8 from spring I 2 is filled with` a suitable.substantially incompressible. I3,

It will be apparent that as the plunger moves to the left.V in Figure 1,the crossfsectional area entering the cylinder is greater than the crosssectional area leaving the cylinder. This coendition tends to decreasethe volume in the cyl,-l inder, but the oil is practicallyincompressible, so that the floating piston 8 is,v forced aga-mst springI2', compressing same. The ratio,` of movement of plunger 2v te piston 8iS; Qf QQlllSe proportionalV t0, the. ratio of the effective areas ofthe plunger and piston, respectively. In practice this ratio will bedesigned( so that. a .large movement of the plunger produces relativelysmall movement of the floating piston. This of course means "that thevelocity of motion is also correspondingly reduced. In the caseoffzextremely high velocityv shocks, suchas would occur if'the device isused as the recoil mechanism for a gun, this reduction in velocity isimportant because the high velocity shockfimpulse on the mountingl endof the spring, in. conventional spring recoil mechanisms, has been'foundto cause a high rate of spring failures. With my device, theaction is also still further slowed down by the throttling effect of thereduced flow .area provided by the flangeY I4v on plunger piston 2Q.This flange provides, in eiect, an orifice of reduced cross-section areato` retard the fluid flow between the left end of the cylinder and theright end. as the plunger piston moves back and forth. The ange thusprovides a ffloatng With the spring l2 compressed as above described',when the compressing force is removed .from plunger 2., the `spring I2,pressing lon floating piston A8, transmits aV force to the exposed areacylinder walls, which acts on the end. of plunger piston 2 to force the`plunger back into its initial position. The piston orices 4in end walls6 and I are provided with suitable fluidtight packing `schematicallyindicated at 6, 1;. and oating piston 8 is similarly provided withpackingl 9, I I, to insure a fluid-tight fit.

Figure 2 shows my invention applied, by VWay of specific example, to agun, such, for example as a light weight aircraft gun. The breech .end

of the barrel 22 serves as the plunger piston in this case, and issurrounded by recoil cylinder 2 l, within which it may slide between thelimits shown in Figure 2 and 3, respectively, the latter representingfull recoil position. In this case, a friction ring spring 32 is showninstead of double coil spring i2 of Figure l, but otherwise all of theelements correspond to those shown in Figure 1, and the operation isexactly the same. As the gun is fired, the recoil forces the barrelbackwards into the position shown in Figure 3, the floating piston 3|moving the short distance shown. This compresses the friction ringspring 32, which thereupon restores the gun to its original batteryposition shown in Figure 2.

If the flange 34 has a symmetrical cross-section at its edge, theiioating throttle, considered as an orifice, will offer the sameresistance to ow in either direction, but if this cross-section is notsymmetrical, as shown in Figures 4 and 5, at 34' (corresponding toflange 34 in Figure 2), the resistance to ow will be greater in onedirection than in the other, due to the difference in turbulence of theflow past the sharp edge and v past the rounded edge, as is wellunderstood in the art. Thus the piston characteristic can be stillfurther altered to speed up or slow down the return stroke relative tothe initial stroke. `In many cases it is desirable to bring the gun torest smoothly at the battery position instead of allowing it to stoprelatively suddenly. This 'caribe provided by the means shown in Figure6. 'In this figure an additional smaller flange 4I is provided behindflange 34 providing in effect a buffer piston which cooperates with anannular recess '42 in floating piston 28. Thus a buffer chamber isformed by flange 4I and recess 42 when the parts are in the positionshown in Figure 6. When the gun barrel is moving back into batteryposition from the position of Figure 6 the buffer piston 4l cooperateswith the recess 42V to provide an additional buimg action. One or morebores 43, 44 are provided between recess 42` and the main cylinder area,with a one-way lvalve 46 between the two bores serving to permit'passage of fluid in the bore only from the cylinder chamber into thebuier chamber, but not vice versa. This, at the start of recoil themovement of the gun barrel is not unusually impeded, fbut' at the end ofthe return stroke a buffing action is' provided.

Although I have shown my invention applied to a gun it will be obviousthat it is equally applicable to other shock absorbing utilization, andthe invention is not limited to the specific embodiments shown, but itsscope is defined by the appended claims.

I claim:

1. A shock. absorber for yieldingly connecting two elements of amechanism subjected to shocks. comprising a cylinder fastened to one ofsaid elements, a plunger extending through said cylinder and fastened tothe other one of said elements, said'plunger consisting of two portionsof different diametric dimensions, a oating piston slidably mounted oversaid plunger within said cylinder dividing said cylinder into two parts,a spring subject to deformation upon relative movement of said twoelements mounted in one of said parts of`said cylinder, said springoperatively engaging said iioating piston and one end of said cylinder,said other part being completely filled with a substantiallyincompressible uid under pressure acting on said iioating piston,whereby said floating piston is held at all times in equilibrium by saidfluid pressure and said spring pressure, an annular throttling flange ofsubstantially larger cross sectional area than said plunger mountedthereon at the jointure between the two-portions thereof, and coaxialsealing means to confine said fluid to said other part, the portion oflarger diametric dimensions of said plunger being moved into said otherpart of the cylinder upon occurrence of a shock whereby the increase inpressure caused by the increase of volumetric displacement by saidplunger is absorbed by said iioating piston and spring to maintainequilibrium therebetween.

2. A shock absorber for yieldingly connecting two separate elements forlimited movement therebetween during shocks, comprising a cylinderincluding two end walls provided with openings therein, a plungerconsisting of two cylindrical tubes of different diameter having anannular throttling iiange of substantially larger diameter than saidtube at the jointure thereof, said plunger extending across saidcylinder through said openings, a iioating piston slidably mounted oversaid plunger within said cylinder and dividing the inside thereof intotwo parts, a spring housed in one part of said cylinder and operativelyengaging said floating piston and one of said end Walls, a substantiallyincompressible fluid under pressure in the other part of said cylinderacting on said floating piston whereby said floating piston is held atall times in equilibrium' between said fluid pressure and said springpressure, said flange being at all times in said other part of thecylinder, and coaxial sealing means located in said openings and in saidiioating piston for coniining said fluid to said other part, saidplunger moving in a direction tending to increase the volumetricdisplacement thereof within said cylinderV in response to shocks,whereby said shocks are absorbed by said floating piston and saidspring.

3. The apparatus accordingY to' claim 2 wherein said spring is of thedouble coil'type.

4. The apparatus according to claim 2 Wherein said spring is of thefriction ring type.

5. A shock absorber for connecting two separate elements for limitedmovement' therebetween during occurrence of shocks, comprising acylinder having end walls provided with openings therein, a plungerconsisting of two cylindrical tubes of different diameter having anannular throttling fiange of substantially larger diameter than saidtubes at the jointure thereof, said plunger extending across` saidcylinder through said openings, a floating piston slidably mounted oversaid plunger within said cylinder and dividing the inside thereof intotwo parts, a spring housed in one of said parts of said cylinder andoperatively engaging said floating piston and one of said end walls, asubstantially incompressible fluid under pressure in the other part ofsaid cylinder acting on said floating piston whereby said oating pistonis held at all times in equilibrium between said fluid pressure and saidspring pressure, said plunger being posi- K tioned in said cylinder withsaid flange at all times in said other part of the cylinder,l -Saidflange having asymmetric, external dimensions offering greaterhydrodynamical resistanceduring movement of said plunger in thedirection of volumetric increase thereof in said other part.

6. The apparatus according to claim 5 further comprising means forsmoothly restoring said Avv Y REFERENCES CITED The following referencesare of record in the file of this patent:

Number 6 UNITED STATES PATENTS Name Date Canetl Mar. 14, 1882 Cook Apr.2, 1918 Harpham Nov. 15, 1921 Griepenstroh July 8, 1941 Thornhill Feb.22, 1944 Dowty Apr. 18, 1944 Bazley Jan. 25, 1949

